Development of characteristic equations and robust stability analysis for SISO move suppressed and shifted DMC

New controller and closed loop transfer functions for move suppressed and shifted dynamic matrix control were derived in order to compare the controller robustness on several plants as a function of tuning parameters X and m. The derivation of these transfer functions are for any order plant requiring its open loop step or impulse response. A generic control,design algorithm was developed for selecting the controller tuning parameters using controller robustness as a performance index, in the presence of plant parameter variations and uncertainties. Shifted dynamic matrix control (DMC) was found to be more robust with respect to all plant parameter variations, and therefore more suited than move suppressed DMC to control plants with wide ranging parameters. This result was demonstrated on an experimental direct current servomotor system, and further verified on a plant having a cascade control structure with the (m,m) being the most robust to plant variations. (c) 2006 ISA-The Instrumentation, Systems, and Automation Society.